Resonant reed relay



Nov. 13, 1962 F. H. OSBORNE RESONANT REED RELAY Filed Dec. 12, 1958 3,054,997 Patented Nov. 13, 1962 thee anteater RESONANT REED RELAY Fred H. Osborne, Snyder, N.Y., assignor to Wurlitzer Company, North Tonawanda, NY, a corporation of Ohio Filed Dec. 12, 1958, Ser. No. 7'79,92 11 Claims. (c1. zen-so This invention relates generally to the art of electric relays, and particularly to a resonant reed relay.

Resonant reed relays are used quite commonly in frequency selective circuits. Remote control garage door operators frequently employ resonant reed relays in order that similar operators in a given location may respond only to a pro-selected signal. Such relays incorporate a tuned vibratory reed having a natural frequency of vibration. When such a reed is exposed to an alternating current field substantially coinciding with its own natural frequency of vibration, the reed will be set in vibration. The vibrating reed then may be used to close a set of contacts intermittently, whereby to effect charging or dis charging of the capacitor, and hence to control the honduction' of an electronic tube, for example.

Reeds as heretofore used in vibrating reed relays have generally been used singly. That is, there is a single vibratin reed cooperating with a more or less fixed contact, often resiliently mounted. Such prior art reeds tend to be somewhat variable as to frequency, depending on the firmness of the mounting. Each such reed reacts on its mount, and the mount damps the reed to a certain extent, thereby in some measure affecting the frequency. If a substantial. mass is used so as to keep the damping at a minimum, then the base may be too heavy for aircraft or certain other applications. On the other hand, if very little mass is used in the base, the base may damp the reed too much, or the reed may transmit too much vibration to the mount and associated parts. Furthermore, physical shock to such a reed can set it in vibration for a sutficient length of time to cause spurious responses. in addition, commercially available vibrating reed relays are limited in sensitivity.

Accordingly, it is an object of this invention to provide a vibrating reed relay which is extremely stable as to frequenc regardless of the mass of the reed mount and regardless of the firmness of mounting.

Furthermore, it is an object of this invention to provide a vibrating reed relay switch which can be tuned within certain limits.

It is an other object of this invention to provide a vibrating reed relay which is extraordinarily shock resistant.

Yet another object of this invention is to provide a vibrating reed relay wherein the reed unit can be tuned in a vice or the like and will remain stable in frequency when placed on a permanent mount.

It is a still further object of this invention to provide a vibrating reed relay having greater inherent sensitivity than commercial units now on the market,

It is another object of this invention to provide a vibrating reed relay utilizing a pair of similar vibrating reeds mounted on an electrically insulating base.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view of a vibrating reed relay constructed in accordance with the principles of this invention;

FIG. 2 is a longitudinal sectional view through the clay taken along the line 22 in FIG. 1;

FIG. 3 is a longitudinal sectional view as taken substantially along the line 3-3 in F IG. 2;

FIG. 4 is a perspective View similar to FIG. 1 showing a modification of the invention; and

FIG. 5 is a fragmentary sectional view of the device of MG. 4 similar to the upper portion of FIG. 3.

Referring now in greater particularlity to the drawings, there will be seen an insulating strip or slab 19 having at its lower or free extremity an aperture 12 for mounting on any suitable support. The strip 10 is provided at its upper end with an aperture 14. An insulating sleeve 16 extends through the aperture 14 and also through similar aligned apertures in the mounting bases 18 of a pair of opposed reeds 24). The reeds are made of spring steel, or other suitable resilient magnetizaole material. The reeds are of identical size and natural vibrational frequency, and are provided at their upper or free ends with a pair of opposed contacts 22 made of any suitable contact metal, and normally spaced out of engagement as shown in FIG. 2. It will be apparent from FIG. 3 that each spacer 18 is rectangular in nature, and that each reed 2% is in the nature of a tongue of restricted width projecting therefrom.

The resonant relay, hereinafter identified by the numeral 24, further includes a pair of brackets 26 of magnetic steel or other suitable magnetically conductive material. These brackets include elongated straplike side members 28 somewhat wider than the reeds 2t and disposed in parallelism therewith. The straps 28 are spaced a substantialy distance from the reeds and are provided at their lower ends with horizontal flanges 3t) coming into contact with the reed bases and then depending as mounting flanges 32. The insulating sleeve 16 extends through these mounting flanges. Insulating spacers or washers 34 are positioned at the oppoiste ends of the sleeve 16, and a screw 36 passes through the insulating spacers or washers 34- and through the sleeve 16. The screw also passes through metal washers 38 on the outer faces of the insulating washers. A nut 40 is threaded on the end of the screw to hold all of the foregoing parts in assembled relation. It will be apparent that the straps or upstanding arms 28 of the brackets 26 are provided near their lower edges or junctions with the horizontal flanges 30 with inwardly struck tongues 42 having the lower edges thereof free.

The resonant reed relay further includes a spool 44 of insulating material. The spool includes an elongated body portion 46 having a circular cylindrical outer surface and a central bore 43 of square cross-section. The bore 43 receives and accommodates the reeds 20, as will be apparent. A coil 5% is wound on the outer surface of the central body portion and is positioned between a square base 52, of relatively small axial dimension, and a square head 54 of relatively greater axial dimension. The head and base preferably are integral with the central body portion 46. The base 52 is provided on opposite sides with notches or recesses 56 receiving the upstanding straps or arms 28 of the brackets 26, while similar recesses or notches S3 in the head 54 receive the upper ends of these arms. The brackets are associated with the spool by an upward movement of the brackets in the position shown, the tongues 42 snapping into place above the base 52 outwardly of the coil whereby to hold the parts in permanently assembled relation.

The coil is provided with an outer wrapping or cover 60 of insulating tape or paper or the like, and the leads 62 of the coil preferably are taken out through the head 54.

The insulating head 54 is provided with a pair of recesses 64 disposed transversely of the central bore 48 and communicating with this bore and also with the recesses 58 receiving the arms 28 of the brackets 26. A pair of cylindrical permanent magnets 66 is mounted in these recesses 64, there being one such magnet for each recess. The magnets are received tightly in the recesses so as to be held frictionally in position, but are movable under force. The magnets are sufficiently short that when their outer ends contact the arms 28 the inner ends terminate just slightly short of the central bore 48. The magnets are mounted with like poles confronting one another, and in the illustrative embodiment it is the north poles that confront one another and hence face on the central bore 48.

Substantially all of the parts of the resonant reed relay now have been disclosed. The only remaining items comprise two terminals 68 in the form of tabs or extensions on the bases 18 of the reeds 26. These terminals conveniently are of a conventional type having apertures for receipt of a wire to be soldered in place, although it will be understood that other suitable types of terminals could be used, including clip terminals or screw thread terminals.

It will be apparent that when the coil or winding 5%) is energized by electrical connection to the lead wires 62, the reeds 6t} serve as a core of an electromagnet comprising the reeds and the coil. The magnetic path from one end of the reeds to the other is very nearly complete through magnetically conductive steel or the like, comprising the brackets 26 which are physically clamped to the reeds at the bases thereof, and further comprising the magnets 66. In the illustrative embodiment, the only air gap is between the north poles of the magnets and the adjacent free ends of the reeds. it will be understood that it is an alternating current potential that is to be applied to the coil. Hence, at one instant the top ends of the reeds (in the position shown in the drawings) will comprise north poles. Although these will tend to repel each other, they will be more strongly repelled by the north poles of the electromagnets, and hence the contacts 22 will be forced into engagement. At a subsequent interval, the upper ends of the reeds will comprise south poles. hese again will tend to repel each other, and further will be attracted by the adjacent north poles of the permanent magnets. Accordingly, the reeds will be deflected away from one another and the contacts 22 will be held out of engagement. Subsequently, the polarity of the reeds will be reversed, and the contacts will be forced toward engagement. Such forcing toward engagement will be augmented by the natural swing of the reeds as they return through the rest position after having been attracted toward the permanent magnets. Obviously, the initial short interval of polarization in any given direction will be insufficient to cause the reeds to deflect sufiiciently to cause contact engagement. A few cycles will be necessary to build up sufficient amplitude of reed vibrations to cause the contacts to engage. If the energizing frequency is not substantially the same as the natural frequency of the reeds, then it will not be possible to build up a sufficient amplitude of vibration for the contacts to close. However, in the present invention the vibrational frequency of the reeds is not solely dependent upon the natural frequency of the reeds. The magnets 66 impose a rather strong force on the reeds. Hence the reeds may be made to vibrate at frequencies slightly different from their inherent natural frequencies. Such forced or semi-natural vibration may be controlled somewhat in frequency by shifting of the magnets longitudinally of their own axis (transversely of the reeds). As will be understood, once the magnets have been placed in proper position, it is a simple matter to add a small amount of cement or other adhesive to hold the magnets permanently in such position.

A preferred embodiment of the invention is shown in FIGS. 4 and 5. Similar numerals are utilized with the addition of the suflix a to identify parts similar to those heretofore shown and described. Repetition of description in many instances therefore is unnecessary. The principal change in the modification resides in the magnetic shunt structure, wherein the brackets 26, as in FIG. 1, are replaced by yokes 26a which are readily removable as for servicing. Each of the yokes 26a comprises a fiat strap or side member 28a fitting over the opposite ends of the head 54a, and having right angularly disposed flanges 76 thereon secured to the head respectively by screws 72 extending through the flanges and threaded into the head. Preferably, the screws are of the fiat head variety, being beveled into the flanges 70.

The reeds 26a are spaced apart at the bottom by an insulating spacer Na, and are spaced from the yokes 24a in magnetic engagement therewith by blocks 74 of steel or other suitable magnetic material. The yokes 26a are apertured near the bottom thereof as at 76 to provide clearance for a screw or the like holding the blocks 74, the reeds Zfia and the insulating spacer 10a together. This construction also facilitates disassembly of the unit for repairs.

A further feature of the modified form of the invention is best seen in FIG. 5. The contacts 22a in this instance comprise rather sinuous wires brazed or otherwise suitably affixed to the faces of the reeds 20a, and relatively crossing one another to insure a proper contact irrespective of precise alignment of the reeds. Operation of the embodiment of P168. 4 and 5, and the parts not specifically noted, are similar to the embodiment of FIGS. 1-3.

The reeds are somewhat analogous to a tuning fork in that they react on one another in the manner of the tines of a tuning fork with substantially no reaction on the base. Hence, the mass of the base and the tightness with which the base is mounted do not materially effect the response of the relay. On the other hand, the reeds are greatly different from a tuning fork in that they are electrically insulated from one another. Obviously, cooperating or opposing contacts on the tines of a tuning fork could accomplish nothing since the tines are integrally formed, and hence at all times in electrical contact or engagement.

It is well known that the natural period of vibration of a reed depends, among other things, on the physical size of the reed. The larger reeds inherently vibrate at lower frequencies than the smaller reeds. Inherently, the larger reeds vibrate with a larger amplitude of vibrations. Since rather small reeds cannot possibly have such a large amplitude of vibration as the larger ones, then any damping of the reeds is sufficient to reduce the amplitude of vibration by a substantial amount. Since the bases of conventional or commercially available vibrating reed resonant relays, utilizing a single reed, necessarily damp the reed to a certain extent, the sensitivity of such units has been limited. In the present in vention the base does not impose any substantial damping effect on the reeds, nor does the mounting means for the base. Accordingly, the unit has a greater sensitivity.

Since the reeds react on one another, shock on the entire unit is unlikely to cause spurious response. Sustained mechanical vibration tends to move the reeds in the same direction. Motion in the same direction will not cause the contacts to close. An individual shock will have the same effect, but coupling between the reeds tends to cause them to move in opposition, as in a tunmg fork. Thus it is apparent that for contact to Occur, the reeds must change the phase of their motion. While this change is taking place a certain amount of damping which is always present reduces the amplitude of motion thus decreasing the chance of unintentional contact occurring after the proper phase relationships between the reeds has been established.

If the magnets are omitted, the resonant reed relay can be actuated by alternating current fed to the coils at sub-multiples of the resonant frequency. The reeds necessarily vibrate in all cases substantially at their resonant frequency, but can be vibrated by sub-multiple frequencies since it is not necessary to inject energy into every cycle of a resonant system to maintain or increase oscillation.

The specific example of the invention as herein shown and described is set forth by way of illustration only. Various changes in structure will no doubt occur to those skilled in the art, and will be understood as forming a part of this invention insofar as they fall within the spirit .and scope of the appended claims.

The invention is claimed as follows:

1. A resonant reed relay comprising a pair of reeds each having a base and a tongue, common means mounting said bases electrically insulated from one another with said tongues extending in parallelism therefrom and having opposed free ends with outer faces and confronting inner faces, said reeds being of magnetically susceptible material and being of substantially the same size and having substantially equal natural frequencies of vibration, the free ends of said reed tongues having contact means on the confronting inner faces thereof and normally spaced apart and capable of engagement upon vibration of said reeds, a coil of wire, means mounting said coil about said reeds for magnetizing said reeds upon electrical energization of said coil, permanent magnet means having a pair of like poles, and means mounting said permanent magnet means with said pair of like poles on opposite sides of and outside of said reed tongues and respectively confronting the outer faces of said reed tongues, energization of said coil with alternating current magnetizing said reeds with the free ends thereof of like but alternating polarity whereby said free ends are alternately attracted by and repelled by said like magnetic poles to set said reeds in vibration toward and away from one another to cause said contact means to come into engagement when the alternating current energization is of substantially the same frequency as the natural frequency of vibration of said reed.

2. A resonant reed relay as set forth in claim 1 wherein the poles of the magnetic means are adjustable relative to the reeds toward and away from said reeds.

3. A resonant reed relay comprising a pair of reeds each having a base and a tongue, common means mounting said bases electrically insulated from one another with said tongues extending in parallelism therefrom and having opposed free ends with outer faces and confronting inner faces, said reeds being of magnetically susceptible material and being of substantially the same size and having substantially equal natural frequencies of vibration, the free ends of said reed tongues having contact means on the confronting inner faces thereof normally spaced apart and capable of engagement upon vibration of said reeds, a coil of wire, means mounting said coil about said reeds for magnetizing said reeds upon electrical energization of said coil, a pair of magnets each having two dissimilar poles, and means mounting the two magnets with like poles thereof outwardly of and on opposite sides of said reeds and confronting respectively adjacent outer faces of said reed tongues, energization of said coil with alternating current magnetizing said reeds with the free ends thereof of like but alternating polarity whereby said free ends are alternately attracted by and repelled by said like magnet poles to set said reeds in vibration toward and away from one another to cause said contact means to come into engagement when the alternating current energization is of the same frequency as the natural frequency of vibration of said reeds.

4. A resonant reed relay as set forth in claim 3 and further including magnetic material means providing a pair of substantially continuous magnetic paths, one such path being between each reed and the pole of the corresponding magnet which is disposed oppositely of that reed.

5. A resonant reed relay as set forth in claim 4 wherein the magnets are adjustable relative to said reeds toward and away from said reeds.

6. A resonant reed relay as set forth in claim 5 wherein the magnetic means providing the magnetic paths comprises a pair of brackets of magnetic material respectively engaging the bases of said reeds and extending exteriorly of 'said coil substantially into engagement with said magnet.

7. A resonant reed relay comprising a pair of reeds each having a fixed end and a tongue, common means mounting said fixed ends electrically insulated from one another with said tongues extending in parallelism in the same direction therefrom and having opposed free ends with outer faces and inner confronting faces, said reeds being of magnetically susceptible material and being of substantially the same size and having substantially equal frequencies of vibration, the free ends of said reedtongues having contact means on the confronting inner faces thereof and normally spaced apart and capable of engagement upon vibration of said reeds, an insulating base having a central body and a pair of enlarged ends, said insulating base having a' bore'extending through said ends and said body longitudinally of said body, a coil of wire on said body and between said ends, means securing said mounting means in fixed relation to said base with said reeds extending through the central bore of said base, and a. pair of magnets carried by said base at one end thereof, said magnets having like poles and respectively confronting the outer faces of the free ends of said reed tongues, energization of said coil with alternating current magnetizing said reeds with the free ends thereof of like but alternating polarity whereby said free ends are alternately attracted by and repelled by said like magnetic poles to set said reeds in vibration toward and away from one another to cause said contact means to come into engagement when the alternating current energization is of substantially the same frequency as the natural frequency of vibration of said reeds.

8. A resonant reed relay comprising a pair of reeds each having a fixed end and a tongue, common means mounting said fixed ends helically insulated from one another with said tongues extending in parallelism therefrom and having opposed free ends, said reeds being of magnetically susceptible material and being of substantially the same size and having substantially equal frequencies of vibration, the free ends of said tongues having contact means thereon normally spaced apart and capable of engagement upon vibration of said reeds, an insulating base having a central body and a pair of enlarged ends, said insulating base having a bore extending through said ends and said body longitudinally of said body, a coil of wire on said body and between said ends, means securing said mounting means in fixed relation to said base with said reeds extending through the central bore of said base, said securing means comprising a pair of brackets, said brackets being made of magnetic material and engaging the fixed ends of said reeds and extending on opposite sides of said coil, said brackets engaging the two ends of said insulating base, and a pair of magnets carried on said insulating base at one end thereof and positioned proximate said brackets whereby said brackets provide a magnetic path between the magnets and the reeds, said magnets having like poles con fronting the free ends of said reeds and on opposite sides thereof, energization of said coil with alternating current magnetizing said reeds with the free ends thereof of like but alternating polarity whereby said free ends are alternately attracted by and repelled by said like magnetic poles to set said reeds in vibration and to cause said contact means to come into engagement when the alternating current energization is of substantially the same frequency as the natural frequency of vibration of said reeds.

9. A resonant reed relay as set forth in claim 8 and further including struck out projections on said brackets engageable with one of the ends of said base for fixing said brackets on said base.

10. A resonant reed relay as set forth in claim 8 wherein the brackets include flanges thereon engageable with side surfaces of the ends of said base and detachably secured thereto.

11. A resonant reed relay comprising a pair of reeds each having a base and a tongue, common means mounting said bases electrically insulated from one another with said tongues extending in parallelism therefrom and having outer surfaces and confronting inner surfaces, said reeds being of magnetically susceptible material and being of substantially the same size and having substantially equal natural frequencies of vibration, contact means on the confronting inner faces of said reed tongues and in confronting relation and capable of engagement with one another, coil means, means mounting said coil means about said reeds for magnetizing said reeds upon electrical energization of said coil means, permanent magnet means having a pair of like poles, and means mounting said permanent magnet means With said pair of like poles on opposite sides of and outside of said reed tongues and respectively confronting the outer surfaces of said reed tongues, energization of said coil means with alternating current magnetizing said reeds with the free ends thereof of like but alternating polarity whereby said free ends are alternatively attracted by and repelled by said like magnetic poles to set said reeds in vibration toward and away from one another to cause said contact means to come into engagement when the alternating current energization is of substantially the same frequency as the natural frequency of vibration of said reeds.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,454 Weightman Jan. 15, 1952 708,539 Fell Sept. 9, 1902 2,275,531 Lakatos Mar. 10, 1942 2,286,800 Gustin June 16, 1942 2,356,791 Huetten Aug. 29, 1944 2,570,315 Brewer Oct. 9, 1951 2,609,464- Brown et a1. Sept. 2, 1952 2,678,360 Bellis May 11, 1954 2,758,173 Riley Aug. 7, 1956 FOREIGN PATENTS 887,530 Germany Aug. 24, 1953 

